Probe-Independent and Direct Quantification of Insulin mRNA and Growth Hormone mRNA in Enriched Cell Preparations

Lommel, Leentje Van; Janssens, Kristel; Quintens, Roel; Tsukamoto, Katsura; Mierde, Dirk Vander; Lemaire, Katleen; Denef, Carl; Jonas, Jean‐Christophe; Martens, Guy; Pipeleers, Daniël; Schuit, Frans

doi:10.2337/db06-0774

Cited by 52 publications

(39 citation statements)

References 33 publications

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“…Beta cells, like plasma cells and thyroid cells, have a high protein load [32,33], synthesising large quantities of (a single) protein. Proinsulin represents up to 20% of the total mRNA and 30-50% of the total protein synthesis of the beta cell [18,19]. These percentages increase further, when considering only cargo (secretory and membrane) proteins synthesised by the beta cell.…”

Section: Discussionmentioning

confidence: 73%

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Increased hexosamine biosynthetic pathway flux dedifferentiates INS-1E cells and murine islets by an extracellular signal-regulated kinase (ERK)1/2-mediated signal transmission pathway

et al. 2011

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Aims/hypothesis Beta cell failure is caused by loss of cell mass, mostly by apoptosis, but also by simple dysfunction (decline of glucose-stimulated insulin secretion, downregulation of specific gene expression). Apoptosis and dysfunction are caused, at least in part, by lipoglucotoxicity. The mechanisms implicated are oxidative stress, increase in the hexosamine biosynthetic pathway (HBP) flux and endoplasmic reticulum (ER) stress. Oxidative stress plays a role in glucotoxicity-induced beta cell dedifferentiation, while glucotoxicity-induced ER stress has been mostly linked to beta cell apoptosis. We sought to clarify whether ER stress caused by increased HBP flux participates in a dedifferentiating response of beta cells, in the absence of relevant apoptosis. Methods We used INS-1E cells and murine islets. We analysed the unfolded protein response and the expression profile of beta cells by real-time RT-PCR and western blot. The signal transmission pathway elicited by ER stress was investigated by real-time RT-PCR and immunofluorescence. Results Glucosamine and high glucose induced ER stress, but did not decrease cell viability in INS-1E cells. ER stress caused dedifferentiation of beta cells, as shown by downregulation of beta cell markers and of the transcription factor, pancreatic and duodenal homeobox 1. Glucose-stimulated insulin secretion was inhibited. These effects were prevented by the chemical chaperone, 4-phenyl butyric acid. The extracellular signal-regulated kinase (ERK) signal transmission pathway was implicated, since its inhibition prevented the effects induced by glucosamine and high glucose. Conclusions/interpretation Glucotoxic ER stress dedifferentiates beta cells, in the absence of apoptosis, through a transcriptional response. These effects are mediated by the activation of ERK1/2.

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Section: Discussionmentioning

confidence: 73%

“…Proinsulin synthesis represents 30-50% of the total protein synthesis of the beta cell [18,19]. In addition, glucose stimulates proinsulin translation [20], as well as increasing the stability of pre-proinsulin and transcription of the insulin gene [21,22], further increasing the protein load.…”

Section: Introductionmentioning

confidence: 99%

Increased hexosamine biosynthetic pathway flux dedifferentiates INS-1E cells and murine islets by an extracellular signal-regulated kinase (ERK)1/2-mediated signal transmission pathway

et al. 2011

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“…Disulfide bond formation in the ER is accompanied by the formation of equimolar amounts of H 2 O 2 as a byproduct (7). In particular in specialized secretory cells, such as pancreatic ␤-cells with insulin as the major biosynthetic product accounting for ϳ50% of total protein synthesis (33,34), the H 2 O 2 generated during the oxidative folding of (pro)insulin could be potentially harmful to the ␤-cell. However, recently, it has been suggested that exogenously added or enzymatically produced H 2 O 2 could contribute either non-enzymatically or via an enzymatic reaction to native disulfide formation (35,36).…”

Section: Discussionmentioning

confidence: 99%

Peroxiredoxin 4 Improves Insulin Biosynthesis and Glucose-induced Insulin Secretion in Insulin-secreting INS-1E Cells

Mehmeti

Lortz

Elsner

et al. 2014

Journal of Biological Chemistry

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Background: Peroxiredoxin 4 facilitates de novo disulfide bond formation by metabolizing hydrogen peroxide. Results: Overexpression of peroxiredoxin 4 improved insulin synthesis and glucose-induced insulin secretion. Conclusion: Increasing the constitutively low expression of peroxiredoxin 4 enhances the ER folding capacity and improves ␤-cell function. Significance: Peroxiredoxin 4 contributes to the preservation of ␤-cell function under conditions of high insulin requirement.

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“…Total RNA from mouse pancreatic islets, acini and whole tissues was extracted and mRNA quantification was performed using Affymetrix mouse 430 2.0 expression microarrays as described (36).…”

Section: Methodsmentioning

confidence: 99%

Interleukin-6 regulates pancreatic α-cell mass expansion

Ellingsgaard

Ehses

Hammar³

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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257

260

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Interleukin-6 (IL-6) is systemically elevated in obesity and is a predictive factor to develop type 2 diabetes. Pancreatic islet pathology in type 2 diabetes is characterized by reduced ␤-cell function and mass, an increased proportion of ␣-cells relative to ␤-cells, and ␣-cell dysfunction. Here we show that the ␣ cell is a primary target of IL-6 actions. Beginning with investigating the tissue-specific expression pattern of the IL-6 receptor (IL-6R) in both mice and rats, we find the highest expression of the IL-6R in the endocrine pancreas, with highest expression on the ␣-cell. The islet IL-6R is functional, and IL-6 acutely regulates both pro-glucagon mRNA and glucagon secretion in mouse and human islets, with no acute effect on insulin secretion. Furthermore, IL-6 stimulates ␣-cell proliferation, prevents apoptosis due to metabolic stress, and regulates ␣-cell mass in vivo. Using IL-6 KO mice fed a high-fat diet, we find that IL-6 is necessary for high-fat diet-induced increased ␣-cell mass, an effect that occurs early in response to diet change. Further, after high-fat diet feeding, IL-6 KO mice without expansion of ␣-cell mass display decreased fasting glucagon levels. However, despite these ␣-cell effects, high-fat feeding of IL-6 KO mice results in increased fed glycemia due to impaired insulin secretion, with unchanged insulin sensitivity and similar body weights. Thus, we conclude that IL-6 is necessary for the expansion of pancreatic ␣-cell mass in response to high-fat diet feeding, and we suggest that this expansion may be needed for functional ␤-cell compensation to increased metabolic demand.alpha-cell mass ͉ beta-cell function ͉ high-fat diet ͉ pancreatic islet

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Probe-Independent and Direct Quantification of Insulin mRNA and Growth Hormone mRNA in Enriched Cell Preparations

Cited by 52 publications

References 33 publications

Increased hexosamine biosynthetic pathway flux dedifferentiates INS-1E cells and murine islets by an extracellular signal-regulated kinase (ERK)1/2-mediated signal transmission pathway

Increased hexosamine biosynthetic pathway flux dedifferentiates INS-1E cells and murine islets by an extracellular signal-regulated kinase (ERK)1/2-mediated signal transmission pathway

Peroxiredoxin 4 Improves Insulin Biosynthesis and Glucose-induced Insulin Secretion in Insulin-secreting INS-1E Cells

Interleukin-6 regulates pancreatic α-cell mass expansion

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